04 The Chromosome Theory And Linkage

The correct answer is "mother" or "female parent" because in Drosophila, the white-eye gene is located on the X chromosome. Since males inherit their X chromosome from their mother, the white-eyed Drosophila male would receive the white-eye gene from its mother. The terms "mom" and "mommy" are informal ways of referring to the mother or female parent.

The Chromosome Theory, proposed in 1902, was put forward by two scientists: Boveri and Sutton. Therefore, the missing last name is Sutton.

When a Drosophila female that is heterozygous for the white-eye gene is crossed with a white-eyed male, the white-eye gene is dominant. This means that all the offspring will inherit the white-eye gene from the heterozygous female, resulting in 100% of the progeny being heterozygous for the white-eye gene. Since white eye is a recessive trait, only individuals that are homozygous for the white-eye gene will exhibit this trait. Therefore, 50% of the progeny will be white-eyed.

In the given experiment, three hybrid cell lines (23, 34, and 41) were produced, and the chart shows which human chromosomes remained in each line. The far right of the table indicates whether the gene product of gene A, B, and C is present in the cells, with a "+" sign indicating presence. Since the answer is "3," it suggests that the gene for B is located on chromosome number 3.

The correct gene order can be determined by analyzing the phenotypes and number of plants in the next generation. By comparing the phenotypes of the F1 generation with the phenotypes of the next generation, we can determine the gene order. In this case, the F1 generation had the genotype ABC, which resulted in the phenotypes ABC, ABc, AbC, and Abc in the next generation. By comparing these phenotypes with the given data, we can see that the genotype BAC corresponds to the phenotype ABC, and the genotype CAB corresponds to the phenotypes ABc, AbC, and Abc. Therefore, the correct gene order is BAC, CAB.

The LOD score, or logarithm of the odds score, is a statistical measure used in genetics to determine the likelihood of linkage between genes based on pedigree analysis. It compares the probability of the observed pedigree data occurring under the assumption of linkage to the probability of the same data occurring under the assumption of no linkage. A LOD score greater than 3 is generally considered significant evidence for linkage, while a score less than -2 suggests evidence against linkage.

Sutton and Boveri noticed that there is a correlation between chromosome behavior and gene behavior. Both chromosomes and genes occur in pairs, and during gamete formation, both pairs of chromosomes and pairs of genes separate. Additionally, the separation of chromosome pairs and gene pairs is independent, meaning that the separation of one pair does not affect the separation of the other pair. Therefore, all of the statements mentioned above are correct.

The progeny of the cross AaBb x aabb show a 1:1:1:1 ratio, indicating that the two gene pairs Aa and Bb are assorting independently. This means that they are located on different chromosome pairs. The distance between two genes on a chromosome is measured in centimorgans (cM). Since the progeny show equal numbers of AaBb and aabb, and AaBb and aabb are the two combinations that result from a recombination event between the two gene pairs, it can be inferred that the two gene pairs are 10 cM apart on the chromosome.

Walter Flemming is credited with the discovery of chromosomes. He was a German biologist who observed and described the process of cell division, specifically the appearance of thread-like structures that he named "chromosomes." Flemming's work laid the foundation for our understanding of the role of chromosomes in heredity and the transmission of genetic information. His discoveries were significant in the field of cytology and paved the way for future research in genetics.